Tumor cell behavior in vivo is influenced by a variety of growth factors, cytokines and connective tissue components. We have analyzed the effect of TPA, cytokines, and the basement membrane component, laminin, on different members of the family of matrix metalloproteinases (MMP-1, MMP- 2, MMP-3, MMP-9) and tissue inhibitors of metalloproteinases (TIMP-1, TIMP-2) in a variety of normal and malignant human cell lines. Enzyme and inhibitor expression was examined by zymography and Northern blots. MMP-2 and TIMP-2 activities were refractory to TPA, IL-1 and TNF-alpha treatment in most of the cell lines. In contrast MMP-1, MMP-3, MMP-9 and TIMP-1 activities were markedly stimulated by TPA in the tumor cell lines and human umbilical cord endothelial cells, whereas the normal fibroblast lines were not, or minimally stimulated by TPA. The increase in activity in response to IL-1 and TNF-alpha was less marked. Northern analysis reflected the zymogram findings for most of the cell lines. Exceptions were the fibroblast cell lines, which showed marked MMP-9 mRNA response to TPA, which was not observed at the protein level. TPA treatment caused increased expression of c-fos containing AP-1 specific binding activity, which was maximal at 6 h and associated with increased expression of MMP- 1, MMP-3 and MMP-9 which possess TPA responsive elements. Laminin has been reported to stimulate metalloproteinase activity. In this study, laminin, the E-8 cell binding fragment of laminin, and a synthetic laminin peptide had no effect on MMP and TIMP activities or mRNA expression. However, commercial "pure" laminin from two different sources contained contaminating metalloproteinases which may have been responsible for the observed increase in MMP activity.